In Wankel et al-type rotary piston mechanisms having a housing comprising end walls spaced apart by a peripheral wall to define therebetween a trochoidal-shaped cavity of one or more lobes and having a piston or rotor, consisting of opposite side faces and a profile forming two or more apex portions, supported for planetary rotary motion in the cavity, a relatively expensive seal grid system is provided. Such sealing grid systems conventionally comprise apex seals at the apex portions of the rotor for engaging the inner surface of the peripheral housing wall, a plurality of side seal strips carried in each side face of the rotor to engage the adjacent inner surface of the end walls, and seal pins carried at each of the apex portions of the rotor to seal the interstices between the side seal strips and apex seals. Also, the seal grid usually includes an oil seal ring carried in each rotor face radially inwardly of the gas seal strips. Each of these aforementioned sealing components are usually biased into engagement with the housing surfaces by springs and/or fluid pressure. Obviously, the fabrication and assembly of such sealing grid systems is time-consuming and costly. In small mechanism applications, as for example, lawn mowers, chain saws, pumps and the like, such relatively expensive sealing grid systems may reduce the competitive advantages of the Wankel-type mechanisms over conventional small reciprocating piston mechanisms. One kown simplified sealing grid system comprises the elimination of the gas seal strips and seal pins on one side face of the rotor and in place thereof provides the rotor with axially extending surfaces for abutment against the inner surface of the adjacent end housing wall. This construction has the disadvantage that the pressure differential acting on the opposite side faces of the rotor applies an axial force against the rotor in a direction toward the rotor side face which has no seal strips or pins to thereby cause too high a friction between that rotor face and the adjacent end wall of the housing.
Accordingly, it is an object of this invention to provide a sealing grid system for a Wankel-type mechanism which is relatively simple, inexpensive and obviates the necessity for apex pins and seal strips on at least one rotor face.
It is an object of this invention to provide a seal grid system for a Wankel-type mechanism which is relatively simple, inexpensive and yet is relatively effective. It is a further object of the present invention to provide a seal grid system for a Wankel-type mechanism which is simple and inexpensive and wherein friction between the rotor and the housing walls is not excessive.
It is a still further object of this invention to provide a seal grid system for a Wankel-type mechanism which is sufficiently effective to be suitable for small sized mechanisms where efficiency is not of paramount importance.
Another object of the present invention is to provide a seal grid system for a Wankel-type mechanism which system permits the use of a side inlet or intake port of larger size than possible with a conventional seal grid system.
A feature of the seal grid system of this invention is the use of conventional seals on one side face of the rotor and sealing axial projections integral with the other side face such that the gaseous pressure forces acting axially on the rotor side faces are substantially balanced.